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TLV713: Power-On behaviour

Uwe Kordmann
Prodigy 10 points
Part Number: TLV713

Tool/software:

Hello,

I am using TLV71333 in a bootstrap circuit for a sigma-delta-converter, compare schematic attached.

The output behaviour is strange. Although the input voltage rises within a few 10µs, the output voltage needs 800µs to rise. My Question is: Why? (waveforms are attached) 

There is only little load on the output (only AMC1106 and 100nF), my calculations say it's definitely not a current limit problem. 

Datasheet doesn't mention any softstart-feature.

Figure 20 in the datasheet is far too unprecice to be of any help.

Please help me.

  • 0
    TI__Expert 4891 points

    Hey,

    Thank you for your question. We're looking into this issue please allow at least 2 business days for a response.

    Thanks,

    Vahnroy

  • 0 in reply to Vahnroy Hosear
    TI__Expert 4891 points

    Hey,

    This behavior is to be expected. You can get a sense of the ramp time from figure 21. You have a higher VOUT setting as well as a higher COUT, which will increase the ramp time.

    Let me know if you have any other questions.

    Thanks,

    Vahnroy

  • 0
    Prodigy 10 points

    Sorry, but your Answer raises more questions than it answers: Figure 21 shows a Vout ramp time of about 150ms, my Vout ramp is about 800µs! And this although I (as you wrote) "have a higher VOUT setting as well as a higher COUT, which will increase the ramp time"?!
    Figure 22 comes closer to my application although I don't understand why in figure 22 the ramp is so much faster than in figure 21.

    But: In both figures Iout rises abruptly to about 50mA. My ramp (1,2V/300µs), together with my output capacitor (100nF) tell me I have about C=I*t/U Iout=C*U/t=100nF*1,2V/300µs=400µA. When adding AMC1106 Iq Iout is <10mA.Shouldn't this increase my Vout ramp significantly?

    Regard my answer as a feedback. I know what I need to know: That I have to search for another LDO :(